MAINTENANCE OF COMPRESSORS

Learning Objective: Recall the inspection points for open-type compressors and repair procedures for common problems in open-type refrigeration compressors.

Inspection points for open-type compressors and repair procedures for common problems in open-type refrigeration compressors are covered in this section.

OPEN TYPES OF COMPRESSORS

Figure 6-61 shows a vertical single-acting reciprocating compressor. Some of the duties you may perform in maintaining this and other open-type compressors are discussed below.

Shaft Bellows Seal

Refrigerant leakage often occurs at the shaft bellows seal with consequent loss of charge. Install a test gauge in the line leading from the drum to the compressor. Attach a refrigerant drum to the suction end of the shutoff valve outlet port. Apply the proper amount of pressure, as recommended in the manufacturer's instructions. Test for leaks with a halide leak detector around the compressor shaft, seal gasket, and seal nut. Slowly turn the shaft by hand. When a leak is located at the seal nut, replace the seal plate, gasket, and seal assembly; when the leak is at the gasket, replace the gasket only. Retest the seal after reassembly. (This procedure is typical for most shaft seals on reciprocating open-type compressors.)

Valve Obstructions

Obstructions, such as dirt or corrosion, may be formed under seats of suction or discharge valves. To locate the source of trouble, proceed as follows:

When the suction side is obstructed, the unit tends to run continuously or over long periods. Connect the gauge manifold and start the unit. This pressure gauge (HI) will not indicate an increase in pressure. The low-side gauge (LO) will fluctuate and will not indicate any decrease in pressure. Clean out any obstructions and recheck again by using the test gauge assembly.

Vertical single-acting reciprocating compressor

Figure 6-61. - Vertical single-acting reciprocating compressor.